Ova Imaria !!link!! -

That is an interesting write-up — though I should note that "OVA Imaria" (often stylized as Imaria or Imāria ) isn't a widely known mainstream anime. From your mention, I suspect you're referring to the 2009 adult OVA Imaria (sometimes listed with the subtitle Shinikare or similar), produced by Studio Eromatick and directed by Yasuhiro Minami.

• “Your happiest memory is a lie. Your saddest memory is a weapon.”
• “Don’t delete the past. You just might delete yourself.”
• “Imaria: Remember nothing. Feel everything.”

Synopsis

Comprehensive Guide: The "Imaria" OVA